Circuit breaker



March 5, 1963 R. T. CASEY CIRCUIT BREAKER 2 Sheets-Sheet 1 Fig.

Original Filed Oct. 7, 1954 /NVENTOR. fimfi y March 5, 1963 R. T. CASEY3,080,462

CIRCUIT BREAKER Original Filed Oct. 7, 1954 2 Sheets-Sheet 2 INVENTOR.

United States Patent 3,080,462 CIRCUIT BREAKER Robert T. Casey,Southington, Conn., assignor to General Electric Company, a corporationof New York Original application Oct. 7, 1954, Ser. No. 460,832, now

Patent No. 2,925,481, dated Feb. 16, 1960. Divided and this applicationSept. 25, 195?, Ser. No. 842,333

7 Claims. (Qt. Nth-$) My invention relates to automatic electric circuitbreakers, and more particularly to small air circuit breakers of thetype used for control of light and power circuits in residentialelectrical systems. This application is a division of my applicationSerial Number 460,882, filed October 7, 1954, issued as Patent Number2,925,481, February 16, 1960, and assigned to the same assignee as thepresent invention.

Circuit breakers of the type referred to are required to be small insize and inexpensive in cost, and, for ease in installation, aredesirably adapted for plug-in mounting. In order to achieve the requiredlow cost, it is desirable that the parts thereof be adapted for assemblyby automated means rather than by manual assembly. In addition, suchcircuit breakers are required to include means whereby automaticinterruption of the controlled circuit is achieved by magnetic orinstantaneous-acting means as well as by thermal or time-delayed means.

For proper operation, certain types of such circuit breakers alsorequire that the relatively stationary contact thereof be resilientlymounted so that when engaged and depressed by the movable contact, adesired amount of resilient pressure is provided to maintain goodcontact pressure in operation.

In circuit breaker constructions of the prior art, these objectives havenot all been adequately achieved by any single circuit breaker, but ineach case, certain objectives are achieved only at the sacrifice ofothers.

It is an object of the present invention to provide a circuit breakerincluding a relatively stationary contact a sembly which, (a) is ofinexpensive, essentially one-piece construction, (b) provides plug-inline terminal means, (0) provides resilient stationary contactsupporting means, (11) provides a source of instantaneous-actingmagnetic force for initiating automatic opening of the circuit breaker,and (e) is adapted to be assembled in the circuit breaker by automatedmeans.

In accordance with the invention in one form, I provide an electriccircuit breaker comprising a generally rectangular insulating casinghaving at least one generally planar wall and provided with an openingadjacent an edge portion of such wall. A terminal member is alsoprovided of fiat resilient strip metal, having end portions return-benton the central portion to form a generally S-shaped member which isadapted to be clipped onto the wall portion by a straight-line movement.The terminal member, when assembled, provides an external portionserving as a plug-in type line terminal, and an inner portion serving toresiliently support a relatively stationary line contact. In addition,the terminal member includes portions which provide additiveinstantaneous-acting magnetic forces for moving the stationary contactin response to predetermined short-circuit currents.

The invention will be more fully understood from the following detaileddescription, taken in conjunction with the accompanying drawings, andits scope will be pointed out in the appended claims.

In the drawings,

FIGURE 1 is a side elevation view of an electric circuit breakerembodying the invention, the enclosing casing being shown in section,the side toward the viewer being removed to show the parts, which areshown in the open condition;

3,080,462 Patented Mar. 5, 1963 FIGURE 2 is a sectional view of thecircuit breaker of FIGURE 1, taken on the line 22 of FIGURE 1;

FIGURE 3 is a view similar to FIGURE 1, the parts being shown in theclosed condition;

FIGURE 4 is a view similar to FIGURE 1, the parts being shown in thecondition existing immediately after automatic opening, i.e., with thethermally responsive bimetallic strip in deflected condition; and

FIGURE 5 is an exploded perspective view of portions of the circuitbreaker of FIGURE 1.

Referring to the drawings the invention is shown as embodied in anelectric circuit breaker including a onepiece open-bottom insulatingcasing 1 containing a circuitbreaker mechanism as set forth and claimedin my aforesaid patent, which is adapted to be pre-assembled andinserted into the casing 1 through the open bottom wall, which isthereafter closed by means of a generaly L- shaped insulating closuremember 40, retained in position by a metallic retaining clip 41.

The operating mechanism assembly comprises a generally U-shaped orbifurcated combination frame and load terminal member 28, having a bightportion 31 and a terminal extension 34.

The member 28 is supported in the casing 1 by having the end portionthereof adjacent the extension 34- supported by the upper end of theclosure member 49, and by having its opposite end portions 3 restingagainst an inner surface of a side wall portion of the casing 1.

The frame member 28 supports a pivot pin 10 which has an elongatedbimetallic strip 7 rigidly attached thereto by suitable means, such asby welding. A movable contact 6 is mounted on the opposite end of thestrip 7 also by suitable means such as by Welding A latch member 14 isalso provided, which is rigidly attached, as by welding, to the end ofthe bimetallic strip adjacent the contact 6, the assembly comprising thestrip '7, contact 6, and latch member 14-, being biased forcounterclockwise rotation about the pivot pin 10 by means of tensionspring 24, connected between the end of the assembly adjacent thecontact 6 and a lancedout eyelet portion 35 of the frame member 28.

The movable contact assembly is adapted to be r0- tated about thepivotal axis of the pivot pin 10 by means of a handle assemblycomprising a generally U-shaped metallic handle-supporting member 12having opposed similar side portions pivotally supported on the pivotpin it between the side portions of the frame member 28, and having itsbight portion extended to provide an extension 19 provided with a detent29 for a purpose to be described.

The handle supporting member 12 also includes extensions or lugs 12aextending in closely fitting relation in recesses in an insulatingmanually operable handle member 13, having a portion extending throughan opening provided in the top wall of the casing 1 for manualengagement.

The insulating handle 13 is provided with an extension 13 adapted toengage a compression spring 26 resting on the bight portion 31 of theframe member 28, by which the handle 13 is constantly biased in aclockwise direction about the pivot pin 10. The handle extension 13'also includes an opening 33 for a purpose to be described.

The handle extension 13' further carries a metallic latch member 32having upturned end portions fitting into corresponding recesses in theextension 13 and having an opening 32A registering with the opening 33of the extension 13.

In accordance with the invention, a combination line terminal andstationary contact supporting member 3 is provided comprising anelongated resilient strip of conductive metal having an intermediateportion 50, a first return-bent portion 51, and a second return-bentportion 52, upon which is mounted a relatively stationary contact member5.

The operation of the invention will be understood by referring first toFIGURE 1, in which the parts are shown in the normal off condition. Inthis condition, the handle 13 is maintained in its extreme clockwiseposition by the action of compression spring 26. The movable contactassembly, comprising the bimetallic strip 7 and the latch strut l t, islikewise biased to its extreme clockwise position' by the tension spring24, the end of the latch member 14 resting on the latch member 32,adjacent the opening 32A.

To ciose the circuit breaker, the handle 13 is moved counterclockwiseabout the pivot pin it), pressing against the end of the latch 14, andmoving the movable contact assembly counterclockwise also about thepivot pin 10, to the closed position as shown in FIGURE 3. When theparts reach the closed position, the detent 29 of the extension 19engages the fixed pin 30 carried by the frame member 23, therebyretaining the parts in the closed position.

When the parts are in the closed position, a circuit exists through thecircuit breaker from the line terminal 3 to the load terminal 34 asfollows: from the line terminal 3 to the stationary contact 5, to themovable contact 6,

through the bimetallicstrip 7, to the pivot pin 1i) and through thebearing engagement of the pivot pin 10 to the frame member 28, andthence to the load terminal 34.

Upon the occurrence of a predetermined overload current in the describedcircuit, the bimetallic strip, which has its high expansion sideadjacent the stationary contact, warps so as to assume a convexcondition with respect to the right-hand side of the circuit breakercasing as viewed. The result of such warping is to move the latched endof the latch strut 14 toward the pivot pin it When this occurs to apredetermined degree, the end of the latch member 14 drops into theopening 32A, permitting the movable contact assembly to be movedclockwise about the pivot pin 10 by the action of the tension spring 24.As the movable contact assembly moves clockwise as described, theintermediate portion of the latch 14 engages the end'of the extension19, disengaging the extension 19 from the pin 30, and allowing thehandle 13 to be moved clockwise by the action of the. compression spring26. The parts at this instant, immediately following thermal tripping,are in the condition shown in FIGURE 4. As the bimetallic strip 7 coolsand resumes its normal straight condition, the end of the latch i4 ismoved out of the opening 32A until it resumes its original latchedposition as shown in FIGURE 1.

Returning again to consideration of the circuit breaker in the oniposition as shown inFIGURE 3, if a short circuit occurs in the circuitcontrolled by' the circuit breaker, the extremely high current, becauseof the nature of thecurrent path, exertsv an instantaneous magneticforce on the movable contact in a clockwise direction. This force istransmitted, through the engagement of the latch 14 with the latchmember 32, to the handle 13, and by the handle 13 to the extension 19,disengaging it from the pin 30, and allowing the springs 26 and 24 tomove the parts at once to the normal off condition 7 as shown in FIGURE1.

The magnetic force referred to is generated by reason of theconformation and positioning of the line terminal strip .3. Thus, as iswell understood in the electrical art, two conductors which arepositioned adjacent each other and which carry current flowing inrelatively opposite directions, will experience a force tending to forcethem It will be observed by inspection of the circuit breaker in theclosed or on position of FIGURE 3, that there is provided three pairs ofsuchclosely spaced oppositeover, arranged so that the magnetic forcesgenerated.

thereby will be additive in their effect on the movable contact assemblyin tending to'move it toward open condition. Thus the portions St] and51 comprise a first pair of such conductor segments; the portions 52 and50 comprise a second pair of such conductor segments; and the bimetallicstrip 7 and the portion 52 comprise a third pair of such conductorsegments. When it is considered that the circuit breaker proper,comprising the insulating casing 1, is rigidly mounted in use, and theportion 51 tightly wedged between a'fixed line conductor, such as a buscar, not shown, it will be seen that all. other portions .mentioned aremovable by reason of the resilience of the strip 3 and the relativemovability of the movable contact assembly. Thus the magnetic repellingforces generated between each of the pairs of conductor segmentsmentioned, are additive in their effect on the movable contact assembly;

In addition'to providing theabove-described magnetic tripping action,the construction of the stationary contact supporting strip Sperforrnsadditional valuable func tions. Thus the return-bend between theportions 52 and 50 provides a resilient support for the stationarycontact 5, which permits it to be depressed by the movable contact 6.The'bend' referred to thereforerprovides the required contact pressureto keep the contacts in tight engagement when the parts are in thenormalon condition, as shown in FIGURE 3. V

In addition, the arcuate construction of the portion of the strip 3external of the breaker casing provides a resilient contact which isadapted to be tightly engaged with a stationary line conductor such as abus bar.

Furthermore, and in addition to the above, the line contact assemblycomprising the strip 3 and the contact 5 provides an assembly which maybe readily assembled on the circuit breaker casing 1 by automated means.Thus 7 the assembly may be assembled on the breaker casing by a simplestraight-line movement, being clipped" onto the side wall of the casingand retaining itself in place by reason of its inherent resilience. Theassembly of the breaker, following the insertion of the mechanismassembly and the stationary contact assembly, is completed bystraight-line assembly of the insulating closure 40 the vertical portionof which is received in the slot 44 of the casing, and the straight-lineassembly of the retaining clip 41 by horizontal movement, during whichits return-bent flanges 47, engage the beads 42 of the casing 1. Theclip 41 is retained in place without further assembly operations by theinwardly bent corners 47a seating in the notches 46 in the beads'42. 1

It will be readily apparent that modifications of the invention may bemade by those skilled in the art, and I therefore intend by the appendedclaims tocover all such modifications as fall within the true spirit andscope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is: a

1. In-anelectric switching device, a, generally rectangular insulatingcasing having side walls and a bottom wall, an opening in said bottomWall extending to the meeting line of said bottom wall and one of saidsi'de walls,ran elongated terminal memberv of flat resilient strip metalhaving portions adjacent the opposite ends thereof returnbent on thecentral portion thereof to form a generally S-shaped member, saidterminal member being adapted to be mounted on said one side wall byfrictional engagement between one of said return-bent portions and saidcentral portion with said return-bentportion on the outside of saidcasing, ajfirst contact surface, adjacent the end of said one of saidreturn-bent portions, for connection thereof to an external conductor,and an electrical contact surface adjacent the end of the other of saidreturn-bent portions for cooperation with a movable con-' tact withinsaid casing and insulatingmeans closing said opening in said bottom walland retaining said terminal in said mounted position.

2. In an electric switching device an insulating casing, a relativelystationary contact in said casing, a generally S-shaped one-pieceterminal member of flat resilient strip metal having a first portionwithin said insulating casing and a second portion extending through awall of said insulating casing to the exterior thereof, said firstportion being generally U-shaped and carrying said relatively stationarycontact on the free end thereof, said second portion extending along anexterior surface of said wall generally parallel thereto so as topresent a substantial contacting surface available for connection to anexternal conductor.

3. An electric circuit breaker comprising a contact member movablebetween on? and on positions, latch means for releasably retaining saidmovable contact member in said on position, said latch means beingreleasable upon the occurrence of a predetermined force upon saidmovable contact in contact-opening direction, a relatively stationarycontact disposed to be engaged by said movable contact when in said onposition, means supporting said relatively stationary contact comprisingelectric current responsive means for moving said relatively stationarycontact in a direction to exert a force upon said movable contact memberin said contact opening direction.

4. An electric circuit breaker comprising a contact member movablebetween off and on positions, latch means for releasably retaining saidmovable contact member in said on position, said latch means beingreleasable upon the occurrence of a predetermined force upon saidmovable contact in contact-opening direction, a relatively stationarycontact disposed to be engaged by said movable contact when in said onposition, means supporting said relatively stationary contact comprisingelectromagnetic force generating means for moving said relativelystationary contact in a direction to exert a force upon said movablecontact member in said contact opening direction.

5. An electric circuit breaker comprising a contact member movablebetween 011 and on positions, latch means for releasably retaining saidmovable contact in said on position, said latch means being releasableupon the occurrence of a predetermined force upon said movable contactin contact-opening direction, a relatively stationary contact disposedto be engaged by said movable contact when in said on position, meanssupporting said relatively stationary contact comprising an elongatedterminal member of flat resilient strip metal having portions adjacentthe opposite ends thereof return-bent on the central portion thereof toform a generally S-shaped member, said relatively stationary contactbeing mounted on one of said ends of said elongated terminal member,whereby magnetic forces generated in said terminal member short circuitcurrents exert a force upon said movable contact member to move ittoward said ofi position.

6. An electric circuit breaker comprising an insulating casing, amovable contact member within said insulating casing movable between onand off positions, latch means for releasably retaining said movablecontact member in said on position, said latch means being releasableupon the occurrence of a predetermined force upon said movable contactin contact-opening direction, a generrally S-shaped elongated terminalmember of fiat resilient strip metal having a U-shaped portion Withinsaid insulating casing and a second portion extending outside of saidinsulating casing, whereby electro-magnetic forces generated in saidU-shaped portion of said terminal member act on said movable contactmember to move it in a contact-opening direction.

7. An electric circuit breaker comprising a contact member movablebetween oil and on positions, means for releasably retaining saidmovable contact member in said on position, said means being releasableupon the occurrence of a predetermined force upon said movable contactin contact opening direction, a relatively stationary contact disposedto be engaged by said movable contact when in said on position, meanssupporting said relatively stationary contact comprising electriccurrent responsive means for moving said relatively stationary contactin a direction to exert a force upon said movable contact in saidcontact opening direction.

References Cited in the file of this patent UNITED STATES PATENTS1,491,799 Haywood Apr. 29, 1924 1,497,241 MacGonigal et a1. June 10,1924 1,738,140 Despard et a1. Dec. 3, 1929 2,037,570 Torsberg Apr. 14,1936 2,182,140 Frank Dec. 12, 1939 2,186,251 Lindstrom Jan. 9, 19402,546,016 Sandin et a1 Mar. 20, 1951 2,623,967 Herman et a1. Dec. 30,1952 2,626,335 Landin Jan. 20, 1953 2,632,826 Titus Mar, 24, 19532,669,613 Despard Feb. 16, 1954 2,841,673 Benander July 1, 19582,856,492 Heyhal Oct. 14. 1958

7. AN ELECTRIC CIRCUIT BREAKER COMPRISING A CONTACT MEMBER MOVABLEBETWEEN "OFF" AND "ON" POSITIONS, MEANS FOR RELEASABLY RETAINING SAIDMOVABLE CONTACT MEMBER IN SAID ON POSITION, SAID MEANS BEING RELEASABLEUPON THE OCCURRENCE OF A PREDETERMINED FORCE UPON SAID MOVABLE CONTACTIN CONTACT OPENING DIRECTION, A RELATIVELY STATIONARY CONTACT DISPOSEDTO BE ENGAGED BY SAID MOVABLE CONTACT WHEN IN SAID ON POSITION, MEANSSUPPORTING SAID RELATIVELY STATIONARY CONTACT COMPRISING ELECTRICCURRENT RESPONSIVE MEANS FOR MOVING SAID RELATIVELY STATIONARY CONTACTIN A DIRECTION TO EXERT A FORCE UPON SAID MOVABLE CONTACT IN SAIDCONTACT OPENING DIRECTION.